Method for manufacturing linen yarn, and linen yarn obtained by application of this method

ABSTRACT

A process for the manufacture of linen yarn in which both twisting and sizing have been eliminated. Instead, the coherence of the fibers is provided by the natural adhesives which, after a specific chemical decomposition of flax, are still present in the resulting fibers. A roving of these fibers is drafted in a wet condition that is defined by the fact that the fibers have a water content between 200 and 350 percent when they are travelling through the drafting device, is false-twisted upon delivery from the drafting device, would to a bobbin at a speed that is substantially the same as the delivery speed of the drafting device, and finally dried.

United States Patent 1 Bok 51 Feb. 20, 1973 [73] Assignee: Nederlandse Organisatie Voor Tolgepast Natuurwetenschappelijk Onderzoek Ten Behoeve Van Nijverheid Handel En Verkeer, .The Hague, Netherlands [22] Filed: April 23, 1971 [21] Appl. No.: 136,724

Leidschendam {30] Foreign Application Priority Data April 28, 1970 Netherlands ..7006240 52 User. ..s7/139, 57/153, 57/164 [51] lnt.Cl. ..D02g 3/40 [58] Field of Search ..57/34 R, 35, 36, 77.3, 139, 57/153, 156, 164; 19/66 [56] References Cited UNITED STATES PATENTS 1,051,361 l/19l3 Young et al. ..l9/66 1,905 ,268 4/1933 Cotchett 19/66 3,447,310 6/1969 Bok et al. ..57/164 3,512,232 5/1970 Bolinger ..57/164 X 3,548,462 12/1970 Naegli ..57/164 X 3,577,872 5/1971 Drummond ..57/164 X Primary Examiner--Werner H. Schroeder Attorney-Brumbaugh, Free, Graves & Donohue [57] ABSTRACT A process for the manufacture of linen yarn in which both twisting and sizing have been eliminated.

Instead, the coherence of the fibers is provided by the natural adhesives which, after a specific chemical decomposition of flax, are still present in the resulting fibers.

A roving of these fibers is drafted in a wet condition that is defined by the fact that the fibers have a water content between 200 and 350 percent when they are travelling through the drafting device, is false-twisted upon delivery from the drafting device, would to a bobbin at a speed that is substantially the same as the delivery speed of the drafting device, and finally dried.

5 Claims, 1 Drawing Figure METHOD FOR MANUFACTURING LINEN YARN, AND LINEN YARN OBTAINED BY APPLICATION OF THIS METHOD The invention relates to a method for the manufacture of linen yarns that are suitable to be used unsized as weaving-yam and knitting-yam, and in particular to such a method in which fibrous material is gained from flax by mechanical operations, this fibrous material is processed into a continuous fiber strand such as a roving or a sliver, the fiber stand is subjected to a chemical treatment that decomposes the fibrous material and brings the pectines, hemi-celluloses and such bonding agents, present in it by nature, into a form in which they are suitable to bring about by drying a mutual joint of the fibers, the fiber strand treated is fed in wet condition to a drafting device so as to be spun into yarn, the yarn is wound into a packet and this packet is dried.

A method of this kind is known, in which the coherence between the fibers in the spun yarn, caused by the natural adhesives, is used in order that a lower value for the twist brought into a yarn upon winding the yarn packet may suffice, so as to be able to decrease the adverse effect of a higher twist on some properties of the yarn, such as the tensile strength.

It is the object of the invention to use the presence of the natural adhesives also considerably to increase the production speed of the yarn, and notably the speed at which the roving or sliver can be spun and wound, and in this way to reach a decrease in the costs of production of the yarn.

The method known in the art cannot yield a considerable increase in velocity. The number of revolutions of the winding device, which is the product of the velocity and the twist number of the yarn, would at constant twist have to be increased to the same extent as the yarn velocity, but for machine-technical reasons and reasons of economy is tied down to a maximum of abt. 12,000 r.p.m.. Neither is, at a constant speed of the winding device, a further decrease in twist a way to realize a higher yarn velocity, because by a decrease in twist the strength of the yarn that in a wet condition moves from the drafting device to the winding device becomes insufficient for the tensions that are unavoidably generated there by the rapid rotation of the winding device.

Nor does the drafting process allow a considerable increase in yarn velocity straightaway. Raising the drafting velocity causes an increase in resistance of the fibers against the mutual displacements, resulting into slip of the fibers between the delivery rollers, which leads to irregularities in the drafting process and eventually to rupture of the yarn. This effect is still intensified by the lubricating-film-effect of the water from the fiber strand, which collects before the delivery rollers, is carried along between them and exercises a pressure that decreases the pressing-force of the rollers.

In view of the said factors it was found that with the method known in the art yam velocities above 40 m/min. could not be used.

It is the object of the invention to provide a method with which the speed limitations described are eliminated or raised such that they are no impediment any more to a considerable increase in production velocity.

For this purpose the method according to the invention is characterized in that the fiber strand is delivered to the drafting device in a substantially saturated wet condition; in that the fiber strand is run into, through and out of the drafting device in upward direction; in that one of the feed rollers of the drafting device is a smooth rubber roller and the other a serrated roller, the hardness of the rubber roller, the shape and the size of the serrations and the pressure of one roller on to the other are chosen in such a connection that the fiber strand after having passed. these rollers still contains at least 200 and at most 350 percent water; in that the delivery velocity of the drafting device is at least 50 m/min.; in that the fiber strand is false-twisted immediately after drafting and is fed to a winding device whose speed of rotation is chiefly equal to the delivery speed of the drafting device.

It is found that drafting the fiber strand, which, after passing the feedrollers, has a water content between 200 and 350 percent, preferably between 250 and 300 percent, at a delivery speedabove 50 m/min., proceeds with a large extent of evenness that still increases at higher speeds, without particular means for an external control of the drafting being necessary. At velocities of 200 m/min. no indications have been found that there would be objections against still further raising the velocity.

This surprising phenomenon must probably be attributed to the viscosity and the mass-inertia of the water in the fiber strand, which, at a suitable mutual relation, cause an even distribution of the occurring acceleration forces and shear forces and of the differences in velocity between the fibers in the drafting field.

It has been found that the correct water content of the fiber strand after passing the feed rollers cannot be obtained and kept constant with certainty when the fiber strand passes through the drafting device in the usual way from the'top downwards. For the excess of water in the fed fiber strand then collects above the pressing-point of the feed rollers, is carried along apart from the fiber strand by theserrations, then comes entirely or partially on the fiber strand and eventually comes in excess on the pressing-point of the delivery rollers, causing side-effects to arise which lead to irregularities and ruptures in the yarn. So as to eliminate this effect it is necessary that the fiber strand is run through the drafting device from the bottom upwards, so that the excess of water pressed out of the fiber strand flows away without collecting before the rollers and being taken along by them.

It is found that false-twisting the drafted fiber strand immediately after it has left the drafting device brings the fibers into such a coherence that thereafter the fiber strand, in spite of the fact that it is then twistless again, is sufficiently strong to be wound. This opens up the possibility to make use of a winding device of the non-twisting type, whose winding velocity may be many times greater than that of the ringspinning spindles and spinning pots required so far because of their twistgenerating action.

Moreover, it is found that it is not necessary to build up the bobbin from strongly crossing windings; apparently the contact between the fibers in the strand is so great that after drying of the bobbin they adhere stronger to each other than to an adjoining parallel winding. Therefore, in the process of winding no rapid traversing movement of a thread guide is required, which still further increases the possible winding velocity. The term straight will be used to refer to the manner of winding the bobbin without twisting, as described in the previous paragraph, and without cross winding as described in this paragraph.

The invention also relates to the yarn that is obtained by application of the method described. It is characterized by the complete absence of twist and any sizing agent but it nevertheless has sufficient tensile strength, wear and shock resistances to be well workable and yields fabrics and knittings that are at least equal to and as a rule better than the corresponding products that are manufactured from twisted yarns according to the method known in the art.

The yarn distinguishes itself in terms of appearance by a somewhat flat cross-section, which arises in drafting and which is permanent owing to the lack of twist. in a fabric the yarn comes to lie flat so that the fabric has a more closed structure and is i.a. particularly suitable to be made windproof and waterproof for application as tent cloth and the like.

Besides, it is surprising that the washability of fabrics and knittings manufactured from these twistless yarns is often better than that of fabrics and knittings that consist of corresponding, twisted yarns.

The invention will be further elucidated below with reference to the drawing, which schematically shows the course of the spinning-process.

Reel 1 contains roving 2, which by mechanical processings is obtained from green, retted or partially retted flax and then is treated chemically with, for instance, successively an alkali hydroxide solution and an alkali chlorite solution. By a proper choice of the concentration and temperature of the solutions and the duration of the treatment the pectines and hemicelluloses present in the fibrous material are brought in such a condition that the elementary fibers, from which the so-called technical fibers, mechanically obtained, are composed, are released sufficiently to be able to shift along each other. After this treatment the wet condition of the roving is preferably maintained for the benefit of the subsequent wet-spinning process.

Wet roving 2 is wound from reel 1, which is freely rotatable, and it is run over guides 3 and 4 through water 5 in trough 6, so that it comes into a saturated wet condition. Instead of running roving 2 through a trough with water, it can also be rinsed with an excess of water, which process makes it saturatedly wet.

Then roving 2 is fed between rollers 7 and 8. Roller 7 is provided with a rubber belt 9. Driven roller 8 at its periphery is provided with serrations, whose height is 1.5 to 2 times as great as the serrations usually employed in known spinning processes. Roller 7 is pressed against roller 8 with a constant force.

By feed rollers 7 and 8 part of the water carried along with roving 2 is squeezed out; the amount that remains inroving 2 is determined by the sizes of the spaces remaining between the serrations and these in turn are dependent on the extent to which the serrations of roller-8 are pressed into rubber belt 9 of roller 7. The

6 various factors are chosen and ad usted such that roving 2 after having passed rollers 7 and 8 still has a water content of preferably 250 to 300 percent.

Via drafting field 10 roving 2 moves freely towards delivery rollers 11 and 12. Driven delivery roller 12 is provided with serrations, which according to shape and dimensions are chosen such that in co-operation with pressing-roller 11, an optimum clamping force is obtained on the fibers leaving the drafting field. Roller 1 1 is provided with a smooth rubber tread l3 and is pressed against roller 12 with a constant force. The pressing-point of delivery rollers 11 and 12 is at a distance of 10 cm from the pressing-point of feed rollers 7 and 8. Scraper 14 serves for the removal of loose fibers, impurities and excess of water, which would remain on roller 1 1.

As a result of the difference in circumferential speeds of feed rollers 7 and 8 and delivery rollers 11 and 12, roving 2 is drafted in drafting field 10 into a thin fiber sliver 15. After having passed delivery rollers 11 and 12 this is carried through vortex chamber 16, in which a very quickly rotating vortex of air is roused by pressurized-air supply 17. In its rotation the vortex of air takes along thin sliver 15, so that the latter is falsetwisted.

Hereafter sliver 15 is wound upon bobbin core 18 into a packet 19, which is rotated at a constant circumferential speed by driven roller 20. This velocity is chosen in such a connection with the circumferential speed of delivery rollers 11 and 12 that sliver 15 is wound up substantially free from tension.

Ready product 19 is taken from the machine and dried, whereafter the thin sliver can be wound from it as a yarn that, without sizing, is normally usable as weaving-yarn and knitting-yam.

I claim:

l. A method for manufacturing unsized linen yarn, including mechanically processing flax to obtain a roving of fibrous material, chemically treating the roving to release the elementary fibers of which the fibrous material is composed and bring the pectines and hemicelluloses present by nature in the flax into a form in which they are suitable to bond the fibers together on drying, wherein the improvement comprises:

saturating the roving with water in excess of 200 to 350 percent;

feeding the saturated roving upwardly between a serrated roller and rubber covered roller;

pressing said rollers together while rotating them in opposite directions to draw the roving upwardly between the rollers and press from the roving all water in excess of 200 to 350 percent;

feeding the roving with 200 to 350 percent water between another serrated roller and another rubber covered roller; 7 pressing the other rollers together while rotating them in opposite directions at a peripheral speed faster than the peripheral. speed of the first mentioned pair of rollers to draw the roving to a thin 5. A linen yarn obtained by application of the process defined in claim 3. 

1. A method for manufacturing unsized linen yarn, including mechanically processing flax to obtain a roving of fibrous material, chemically treating the roving to release the elementary fibers of which the fibrous material is composed and bring the pectines and hemi-celluloses present by nature in the flax into a form in which they are suitable to bond the fibers together on drying, wherein the improvement comprises: saturating the roving with water in excess of 200 to 350 percent; feeding the saturated roving upwardly between a serrated roller and rubber covered roller; pressing said rollers together while rotating them in opposite directions to draw the roving upwardly between the rollers and press from the roving all water in excess of 200 to 350 percent; feeding the roving with 200 to 350 percent water between another serrated roller and another rubber covered roller; pressing the other rollers together while rotating them in opposite directions at a peripheral speed faster than the peripheral speed of the first mentioned pair of rollers to draw the roving to a thin fiber sliver and deliver it at a delivery speed of at least 50 m/min.; false twisting the sliver; winding the sliver onto a winding device.
 2. The method defined in claim 1, wherein the sliver is wound straight onto the winding device.
 3. The method defined in claim 1 wherein the water content of the roving in the drafting field between said pairs of rollers is 250 to 300 percent.
 4. A linen yarn obtained by application of the process defined in claim
 1. 